The mission of the NIEHS Microarray Group (NMG) is to develop and advance an intramural research program that utilizes the advances in genomics to address critical threats to human health as a consequence of environmental exposures. Specifically, the NMG is incorporating genome-wide gene expression analysis using microarray technology as well as emerging gene expression analysis technologies and developing bioinformatics approaches to address the NIEHS mission of reducing or eliminating these threats to human health. Thus the goals of the NMG include: 1) the pursuit of mechanistic investigations of the impact of exposures on gene expression and alterations in critical cellular regulatory pathways, 2) the utilization of global gene expression changes following environmental stresses to identify specific changes, using bioinformatics tools, that are tightly linked with a deleterious human health outcome as patterns or biomarkers of a particular disease or toxic outcome, and 3) the continual development and implementation of new and better approaches to investigate genome-wide changes in gene expression. One consequence of this research program will be the accumulation of global gene expression information that will contribute to the population of the NCT environmental health and toxicogenomics gene expression knowledgebase, CEBS.